Christian influences on the Islamic world

Christian influences in Islam can be traced back to Eastern Christianity, which surrounded the origins of Islam. Islam, emerging in the context of the Middle East that was largely Christian, was first seen as a Christological heresy known as the "heresy of the Ishmaelites", described as such in Concerning Heresy by Saint John of Damascus, a Syriac scholar.

Christians introduced the Muslims to Greek learning. Eastern Christian scientists and scholars of the medieval Islamic world (particularly Nestorian Christians) contributed to the Arab Islamic civilization during the Umayyad and the Abbasid periods by translating works of Greek philosophers to Syriac and afterwards to Arabic. They also excelled in philosophy, science, theology and medicine.

Scholars and intellectuals agree Eastern Christians have made significant contributions to Arab and Islamic civilization since the introduction of Islam, and they have had a significant impact contributing the culture of the Middle East and North Africa and other areas.

Christian communities have played a vital role in the Muslim World. Pew Research Center estimates indicate that in 2010, more than 64 million Christians lived in countries with Muslim majorities (excluding Nigeria). The Pew Forum study finds that Indonesia (21.1 million) has the largest Christian population in the Muslim world, followed by Egypt, Chad and Kazakhstan. The majority of Muslim countries also use a Gregorian calendar and some countries observe Sunday as a non-working day (cf. Sunday Sabbatarianism).